"Śāstra" (शास्त्र) is Sanskrit for "rules" in a general sense. The word is generally used as a suffix in the context of technical or specialized knowledge in a defined area of practice; e.g. Bhautika Shastra (physics), Rasayana Shastra (chemistry), Jeeva Shastra (biology), Vastu Shastra (architectural science), Shilpa Shastra (science of sculpture), Artha Shastra (economics), and Neeti Shastra (political science). In essence, the shaastra is the knowledge which is based on principles that are held to be timeless. Shastra means suffix 'logy' for the subjects; like in English language suffix word 'logy' (e.g. ecology, psychology etc.), 'Shastra' is suffix. it means scientific and basic knowledge on particular subject.